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This Week's Feature Composite Example

Micro Crack Density Prediction of Continuous Fiber Reinforced Polymeric Composites

Figure 1 - Typical micro cracks in polymer matrix composites

Cryogenic polymer composite propellant tanks are widely employed in Reusable Space Vehicles due to their lightweight. However, micro crack can cause loss of stiffness, stress re-distribution, material degradation due to moisture and oxidation, and leakage when micro-damages exceed tolerable levels which may cause catastrophic tank failure. Micro-cracks (Figure 1), formed in the polymer matrix during manufacturing and service, significantly contribute to the leakage of composite propellant tanks. Therefore, predicting micro-crack formation and development in cryogenic tanks is of great importance to tank design.
Figure 2 - Comparison between the simulated crack densities and test data in 90-degree plies of two IM600/Q1334 laminates under monotonic tension.

GENOA's prediction of the crack density in a polymer composite structure includes three parts: 1) onset of cracks in the structure, 2) multiplication of cracks through the entire structure, and 3) degradation of composite properties due to the existence of cracks at each location. Crack density is obtained at the ply level in the laminate at each location of the structure. 
Figure 3 - Crack density development in the 90 degree plies of the IM7/977-2 laminate under tension fatigue in the 0 degree direction. Laminate configuration is [0/45/90/-45]

  

Figure 2 illustrates the micro crack initiation and propagation in two IM600/Q1334 laminates under monotonic tension [1]. The crack density developments in an IM7/977-2 quasi-isotropic laminate under isothermal fatigue loads (room and cryogenic temperatures) were predicted and verified against Air Force test results (Figure 3) [2].

 

Click here to receive demo and presentation of Micro Crack Density.

 

References:

1. Su, X., Abdi, F. and J. Andre Lavoie, "Prediction of Micro-crack Densities in Cryogenic IM7/977-2 Propellant Tanks", 45rd AIAA Structures, Structural Dynamics, and Materials Conference, AIAA-2006-1933. Click here to read technical publication.

2. Su, X., Abdi, F. and Kim, R.Y., "Prediction of Micro-crack Densities in IM7/977-2 Polymer Composite Laminates under Mechanical Loading at Room and Cryogenic Temperatures," 46rd AIAA Structures, Structural Dynamics, and Materials Conference, AIAA-2005-2226. Click here to read technical publication. 

Click here to read the full technical product data sheet of GENOA.
 

Did You Know?

Modeling Multiple Plies Using a Single Shell Element

imageUnlike many Finite Element Solvers, GENOA is able to model multiple plies (laminate) using a single shell element layer. In many FE solvers, the analyst has to model several layers of shell elements to assign plies in a laminate to each layer which increases the computation time significantly.  GENOA's single shell element modeling of plies offers easier assignment and faster performance.  For more information on trying out GENOA through our demos, please contact our sales at sales@ascgenoa.com.

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